Transtage American space tug. Flown 1968-1982 on Titan 3A and 3C boosters. Transtage mass remaining after insertion of Dynasoar and Abort Stage into orbit. Transtage had its own RCS. Maneuver in earth orbit. More...

Space Tug American space tug. Study 1971. The original Boeing Space Tug design of the early 1970's was sized to be flown either in a single shuttle mission or as a Saturn V payload. Optimum mass was found to be 20.6 metric tons regardless. More...

ATV ICC European space tug. Study 1985. The Integrated Cargo Carrier was located at the forward end of the ATV. It represented 60% of the total ATV volume and carried all of the cargo for resupplying the Station. More...

ATV SM European space tug. Study 1985. The unpressurized ATV Service Module included propulsion systems, electrical power (including solar arrays), computers, communications and most of the avionics. More...

OTV American space tug. Studied 1985-1989. The Orbital Transfer Vehicle was reusable space tug, powered by Lox/LH2 engines and equipped with an aerobrake allowing it to be returned for refueling and reuse at an orbiting space station. More...

HTV Japanese unmanned spacecraft designed for launch by the H-IIB launch vehicle for International Space Station resupply. The HTV carried International Standard Payload Racks, and was docked using the ISS robot arm after rendezvous with the station. First launched 2009.09.10. More...

ERTA Russian space tug. Study 1992. ERTA (Elecktro-Raketniy Transportniy Apparat) was a nuclear-electric space tug designed to be boosted on medium boosters and provide both propulsion and electrical power for unmanned planetary probes. More...

Progress M-SO Russian docking and airlock module for the International Space Station. First launch 2001.09.14. Delivered to the station by the Progress service module, which was jettisoned after docking. More...

ATV European logistics spacecraft and space tug. The Automated Transfer Vehicle was first proposed in the mid-1980s as a way to transport unmanned cargo to a Space Station. Operational in that role, first launch 2008.03.09. Studies for a manned version with a re-entry capsule conducted, but no funding for development. More...